#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <math.h>


int main()
{
	int i = 0;
	int count = 0;
	long long sum = 0;
	int s[30] = { 0 };
	while (scanf("%d", &s[i]) != EOF)
	{
		sum += s[i];
		i++;
		count++;
	}
	sum *= (long long)pow(2, count - 1);
	printf("%lld", sum);

	return 0;
}